1. Field of the Invention
This invention relates to a laser light irradiation apparatus, which irradiates laser light to living tissues of an animal such as a human body to permit an incision, vaporization of the living tissues or a thermal therapy and, more particularly, to a laser light irradiation apparatus by which a thermal therapy can be carried out efficiently for cancer tissues and the like while the penetrating member of the laser light irradiation apparatus is brought into contact with the surface of the living tissues directly or through the intermediary of a surface layer on the penetrating member.
2. Prior Art
Medical treatments such as incisions of living tissues of animal organisms by irradiation with laser light are conspicuous due to the ability of hemostasis.
It had been the conventional method that the laser light was irradiated from the fore end of an optical fiber which is held out of contact with the living tissues. This method, however, causes severe damage to the fore end portion of the optical fiber. Therefore, a method which has been utilized lately is as follows;
First, laser light is transmitted into an optical fiber, whose fore end portion is located adjacent to the treated living tissues. Next, the laser light fed out from the fore end of the optical fiber is applied to an emitting probe, which can be held in contact or out of contact with the living tissues. Then, the laser light passes through the probe and is emitted from the surface of the probe for irradiating against the tissues. In this case, it is preferred that the probe be brought into contact with the living tissues (hereafter "living tissue" is sometimes expressed by "tissue" only).
The Applicant developed many kinds of contact probes which are utilized for various purposes.
Further, lately, localized thermal therapy is drawing special attention as a carcinostatic therapy. According to this method, cancer tissues are destroyed by keeping the cancer tissues at a temperature of about 42.degree.-44.degree. C. for 10-25 minutes by irradiation with laser light. The effectiveness of this method has been reported by the inventors in the Bulletin of Japan Society of Laser Medicine, Vol. 6, No. 3 (January 1986), pp. 71-76 and 347-350.
On the other hand, considerable attention has been paid to laser-chemical therapies including the method reported in 1987 by Dougherty et al of the United States. According to this method, 48 hours after an intravenous injection of a hematoporphyrin derivative (HpD), weak laser light such as argon laser or argon pigment laser is irradiated against a target area of the treatment. Whereupon oxygen of the primary term which as a strong carcinostatic action is produced by HpD. Since then, there have been published various reports in this regard, including the one in the Bulletin of Japan Society of Laser Medicine, Vol. 6, No. 3 (January 1986), pp. 113-116. In this connection, it has also been known in the art to use "pheophobide a" as a photo-reactant. Further, recently, YAG laser has been put into use as a laser light source.
In the above mentioned medical treatment, it is important that the laser light is irradiated uniformly for the cancer tissues and, in case of the thermal therapy, it is particularly important that the cancer tissues are heated uniformly.
However, it is very difficult to irradiate the laser light uniformly and it is further difficult to irradiate against a broad target area. Therefore, a following method should be carried out;
The laser light is repeated to be irradiated against each small part of the target area separately so that the whole target area can be irradiated. Accordingly, it takes a long time to perform the medical operation.
Under these circumstances, laser light irradiation apparatuses having a plural number of laser light emitters or probes were studied. With the apparatus of this type, the laser light emitted from the probes is irradiated simultaneously against the tissues. Such laser light irradiation apparatus was shown also by Applicant in Japanese Patent Application No. 62-50723.
It is sure that the laser light can be irradiated against the tissues uniformly to some degree with these apparatuses. However, uniformity is not enough. On the other hand, the plural number of laser light conduction passages and probes, and a controller for the passages and the process are necessary in these apparatuses, therefore increasing cost.